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Muffler advice

956 views 13 replies 3 participants last post by  Beechkid 
#1 ·
I have a 390 in my '64 TBird completely rebuilt with a Lunati "Voodoo" hydraulic roller cam, the mildest one of that series. Other mild performance modifications including 9.7 compression, a roller timing set and tappets. Also a set of shorty headers and a custom 2-1/2" exhaust. A "friend" (note that is in quotes) sold me a pair "lightly used" of Magnaflo mufflers and they have proven to be just too loud. I had a set of Hushpower mufflers added downstream (just before the tailpipe exit) and that made a substantial improvement. However the system drones on the highway.

Any suggestions on a quiet muffler to replace the Magnaflos? Mine are 14" long and I don't have room to go larger. They have inboard entrance and exit, and I want to keep that configuration to avoid messing up the rest of the exhaust.

My goal is the quietest available without completely screwing up my performance modifications.
 

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#2 ·
I would recommend saving a lot ofmoney & go with Allied resonators......available is any muffler shopnationwide, are of excellent quality, 1/2 the price of “performance Mufflers”,available in any length from 10" to 38" (IIRR), flow as good as Borlaor most any of the "Race Mufflers”, tone is deeper and you get a nicerumble (low) with no drone and none of the tinny "ricer" echo. Alliedhas been made for at least 30 years and available in just about any diameteryou would require (I have personally run these for since the 1970's....nice lowrumble on acceleration & deceloration, no drone, deep tone.


The muffler shop should also be able to drop your system, hold up different length units to see what fits your ears best. On my 65 Mustang (300 hp 289), I run 3" diameter x 28" length, with 2" diameter tail pipes
 
#6 ·
Well this is weird. Their catalog doesn't show a muffler with my configuration at all, which is offsets on the same side.

http://team-allied.com/p-33573-team-street-series-style-armor-max-flow-sale-exhaust.html


I may be wrong, but I don't think that is the allied I'm referring to...they have multiple mfg sites in the US, they use to and may still have contracts to build many of the name brand mufflers (flowmaster use to be one)...............just visit your favorite muffler shop.........
 
#4 ·
I just reminded myself of my wild high school days driving my '72 Ford LTD with a 351W 2V with a single exhaust. I was taking a road trip after work on a Friday and my muffler separated from the engine pipe on a speed bump. I checked under to see that everything was secure, or at least wouldn't fall off, and I couldn't afford the delay so I headed out to the highway for my 2 hour hour drive.

I had that car tuned very nicely with initial spark advance well into the teens and it would mildly backfire under decelleration. Without the muffler though that backfire sounded like automatic weapons fire. I passed a guy on the highway then let up on the gas when I was ahead of him and he got the full impact. The poor fellah must have thought he was getting shot at because he hit the brakes so fast he almost lost control.
 
#8 ·
They make just about everything.....and the offset mufflers you are referring to can just be flipped.....but I would look strongly at the resonators (ie glasspack style) ie. bullet units......any shop can fabb those up into place
 
#9 ·
Summit finally responded to my email and were not helpful. Apparently the only muffler in the world with offset pipes on the same side resides under my car.
 
#10 ·
OK the next way to go is a 14" long oval or square with a center inlet offset outlet. I'll have to revise a short section of the existing pipes but that shouldn't be a huge deal. Here's Summit's selection:

https://www.summitracing.com/search...doSKU&SortBy=DisplayPrice&SortOrder=Ascending

It looks like the AP brand is probably what you referred to earlier. No reviews, no claims on performance either.

The Summit brand looks exactly like the Magnaflo 11226. It's probably what I have now.

No info at all with respect to volume reduction.
 
#11 ·
The opposite side offset option on Summit's site points me to a Dynamax 17734. They have a decent website were they define quietest to loudest and even have some sound clips. The problem is the configuration isn't going to make pipe modifications very easy.
 
#14 · (Edited)
Ok, here is everything you wanted to know about db's, sound & flow..........

broaderperformance.com/muffler_flow_tests.htm(Independently tested cfm flows of the more popular mufflers, glasspacks andresonators @ 15” wc:

2 ½” diameter straight pipe 521
2 ¼” diameter straight pipe 365
2” diameter straight pipe 283
2 ¼” diameter tailpipe 268
2 ¼” round glasspack- no louvers 274
2 ¼” round glasspack- with inwardpunched louvers 133
2 ¼” round glasspack- inwardpunched louvers/installed backwards 141
2 ½” inlet/outlet DynomaxSuperTurbo 268
2 1/4” inlet/outlet Thrush CVX 260
2 ½” inlet/outlet Flowmaster2-chamber 249
2 ¼” inlet/2 ½”outlet Cherry Bombturbo 249
2 ¼” inlet/outlet Flowmaster3-chamber 229
2 ¼” inlet/2 ½”outlet MaremountSuper C (OEM Replacement) 149
2 ¼” inlet/2” dual outlet Maremount 183
2 ¼” inlet/outlet California Turbo 229
2 ½” inlet/outlet HookerAerochamber 324
2 ½” inlet/outlet Hooker MaxFlow 521
2 ¼” inlet/outlet MaremountCherrybomb Vortex 298
2 ½” inlet center/outlet offsetBorla Turbo 373

I have listed here amuffler shootout test done by CAR CRAFT:

The Mufflers
MAKE MODEL Part No.
SUMMIT Turbo 630125
THRUSH Magnum Glasspack 24214
THRUSH Boss Turbo 17718
HOOKER Competition 21006
DYNOMAX Super Turbo 17733
DYNOMAX Race Magnum 24215
HOOKER Super Competition 21106
SUMMIT Fully Welded 630325
FLOWTECH Afterburner 50322

MUFFLER FLOW TEST

MUFFLER Flow at 28-in H20
DynoMax Race Magnum 528.64 cfm
Thrush Magnum Glasspack 507.40 cfm
Summit Fully Welded 343.38 cfm
Flowtech Afterburner 342.20 cfm
DynoMax Super Turbo 333.94 cfm
Hooker Competition 232.46 cfm
Hooker Super Competition 320.96 cfm
Summit Turbo 331.16 cfm
Thrush Boss Turbo 297.36 cfm

MUFFLER Idle dB WOT dB
DynoMax Super Turbo 89 123
DynoMax Race Magnum 94 133
Flowtech Afterburner 92 124
Hooker Competion 92 122
Hooker Super Competion 90 125
Summit Turbo 89 124
Summit Fully Welded 92 125
Thrush Boss Turbo 90 123

Thrush Magnum Glasspack 92128

DYNO TEST
All mufflers were dyno-tested on a 355-cube SBC with 10.0:1 compression, AirFlow Research 190 aluminum heads, a CompCams 292 hyd. a Victor Jr. intake, aHolley 750-cfm double-pumper, and 1 5/8 Headman headers.

MUFFLER HP TORQUE 2,500-6,000rpmAverage
Hooker Competition 397.4 381.1 286.8hp/351.9 lb-ft
Thrush Boss Turbo 407.1 384.9 292.1 hp/357.5 lb-ft
DynoMax Race Magnum 409.5 394.3 298.8 hp/366.9 lb-ft
Flowtech Afterburner 409.7 391.2 294.8 hp/361.7 lb-ft
Thrush Glasspack 409.5 389.8 297.7 hp/365.3 lb-ft
Summit Turbo 411.5 386.3 291.5 hp/357.4 lb-ft
DynoMax Super Turbo 412.7 387.2 292.6 hp/358.6 lb-ft
Hooker Super Comp 413.8 387.2 292.8 hp/359.0 lb-ft
Summit Fully Welded 415.4 390.7 295.6 hp/362.4 lb-ft

While there are mufflers that willout flow a glass pack design, it also depends on the design. Does the glasspackuse "louvers or perforations" - Louvers reduce the flow by as much as50% but Allied resonators (that typically sell installed for about $80) each and available at anymuffler shop) independent test flowed 90%+ of a"race spec muffler". Others using other brands consistently showedsimilar results. These are available at any muffler shop nationwide, are ofexcellent quality, 1/2 the price of “performance Mufflers”, available in anylength from 10" to 38" (IIRR), flow as good as Borla or most any ofthe "Race Mufflers”, tone is deeper and you get a nice rumble (low) withno drone and none of the tinny "ricer" echo.

Now for the H versus X pipe..........

The H-Pipe really plays verylittle in terms of performance- nor does it reduce backpressure in any way- itwas originally introduced to equalize the pressure between the two pipes,inducing a scavenging effect, but in reality, while it did improve some thingsa little, all it really, the only thing it really was effective at was toreduce noise- nothing more.

An X-pipe will increase HP if itis installed at the "area of confusion" (just like where the H-pipe should be located)- but that area is identifiedby painting a small strip on the exhaust pipes about 1/2 way between the engineand the axle- the area of confusion will cause increased heat and blister/burnthe paint at that location- that's where the H or X pipe would be installed-and eliminates the air flow disturbance by sending alternating pulses in thatlocation which acts as a "vacuum" if you will to push & scavengethe remaining and incoming air out....if you just threw it on, well, the effects are anywhere from none to acting like a partial cork inside the system.

http://www.popularhotrodding.com/eng...../index1.html (this is an in-depth article that tests not only themis-conception of flow demand but also how placement of a muffler (a glass packin this dyno test) can actually "fool " the system into thinking thatit is essentially a straight pipe.

ok everything you always wanted to know...................



 
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